An algorithm to align spatially sequential, parallel images of autoradiographs showing cerebral metabolic activity in microtomed sliced sections of experimental animal brains has been developed to facilitate arbitrary plane viewing in the three-dimensional image space resulting from the stacking of aligned paralled images. Use of the algorithm, which is based on minimizing non-overlapping areas, demonstrates the need for fixed fiducial reference points in specimen images. Preliminary attempts in preparing specimens to provide fiducial points illustrate the difficulty of this task. LCM will continue algorithm development on the newly installed NIMH De Anza Imaging System. CSL will remain available for consultation.